Dehydration is the main cause of water retention in the body, according to APEC Water. When the body does not receive a sufficient amount of water, it reuses existing water so that it can regulate essential health functions.
Insufficient water in the body causes the liver to do extra work that the kidneys normally do, states APEC Water. The body reacts to dehydration by increasing a hormone that signals the kidneys not to filter existing water. The body reuses the available water for critical health aspects, such as brain function, filtering toxins, transporting nutrients, balancing electrolytes and organ lubrication. Water retention and bloating continue until proper hydration restores the normal equilibrium.